Learning is a remarkable process that enriches our lives by allowing us to rapidly acquire new skills, interact with novel tools and environments, and maintain memories of those experiences. Across a broad range of motor tasks, humans show a stereotypical learning function: an initial rapid decrease in errors followed by a slower, gradual reduction in error. It has been hypothesized that this learning curve reflects the operation of two processes, one based on strategic control and a second involving sensorimotor recalibration. By this view, strategic control, when available, quickly reduces large errors during the initial phase of learning. The sensorimotor recalibration operates with a slower time constant to gradually reduce errors throughout learning. Our first experiment will use a visuomotor adaptation task in which errors are either introduced abruptly or gradually. The former should engage both processes;for the latter, learning will be restricted to the sensorimotor recalibration process. Using a model-based approach, within-hand generalization and between-hand transfer will be used to identify the reference frame underlying the new sensorimotor mapping under these two processes of learning. A second series of experiments will examine the contribution of the dorsolateral prefrontal cortex to motor learning through its role in the strategic control process. Neuroimaging and patient research will be used to explore this question. Taken together, the experiments will aid in determining both the computational processes and neural circuits underlying motor learning. Stroke and neural disease can lead to a profound loss of motor ability, significantly impairing daily function. The N.I.H. identified the need to develop novel training methods to restore function in neurologically disabled individuals in its report "Neuroscience in the New Millennium." This project aims at examining how two different processes, reliant on distinct neural circuits, contribute to motor learning. These processes may be important for designing rehabilitation programs that are tailored to exploit learning and control systems that remain functional.